Apparatus and method for extrusion of thin-walled tubes

• US 20050042402A1
• Filed: 09/22/2004
• Published: 02/24/2005
• Est. Priority Date: 10/30/2001
• Status: Active Grant

• Current Assignee: Lifeshield Sciences LLC (Acacia Research Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Wolek, Howard, Hill, Jason P., Girton, Timothy S., Sogard, David J., Venditti, James, Wong, Alice, Brodeur, Christopher B.
• Granted Patent: US 7,425,291 B2
• Time in Patent Office: Days
• US Class Current: 428/35.700
• CPC Class Codes: B29C 45/531 Drive means therefor
• CPC Class Codes: B29C 48/0012 combined with shaping by internal pressure generated in the material, e.g. foaming
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 48/475 using pistons, accumulators or press rams
• CPC Class Codes: B29C 48/48 Two or more rams or pistons
• CPC Class Codes: B29K 2027/18 PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29L 2023/007 Medical tubes other than catheters catheters B29L2031/7542
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/139 Open-ended, self-supporting conduit, cylinder, or tube-type article

Abstract

The present invention provides an apparatus and method for manufacturing polymeric thin-walled tubular members, which are well-suited for use as vascular grafts. The apparatus of the present invention enables extrusion of a tubular member having an extremely thin wall thickness so as to facilitate passage through tortuous vascular passageways. The apparatus achieves uniform wall thickness in a tubular member by establishing and maintaining axial alignment of a ram having a concentrically disposed guide rod therein with a die supported in concentric relation to the guide rod.

Claims

1. A thin-walled tubular member extruded by an apparatus for extrusion of at least one thin-walled tubular member from a pre-form of polymeric material, said apparatus comprising:

an extrudate die having an orifice formed therethrough;

a barrel having a bore in communication with said orifice;

a piston slideably disposed in said bore;

a ram mounted to said piston; and

a guide rod extending through said bore, said guide rod being constrained so as to maintain a relatively constant annular gap between said barrel and said guide rod.

2. A tubular member as in claim 1, wherein said tubular member has a wall thickness of less than or equal to about 250 μ

m.

3. A tubular member as in claim 2, wherein the tubular member is formed of PTFE.

4. A tubular member as in claim 1, wherein the tubular member is formed of PTFE.

5. A process for forming a tube, said process comprising the steps of:

extruding a tubular member having a lumen; and

injecting a stable medium into said lumen of said tubular member to provide structural support therefor.

6. A process as in claim 5, wherein said stable medium is air.

7. A process as in claim 5, wherein said tubular member is extruded from a fluoropolymer.

8. A process as in claim 7, wherein said fluoropolymer is PTFE.